1. Field of the Invention
The present invention relates to pressure loss as a result of friction in the flow of hydrocarbon fluids through conduits, and more particularly to additives for reduction of friction encountered in the flow of hydrocarbon fuels through conduits.
2. Description of the Prior Art
Hydrocarbon fuels are often transported by conduit over vast distances. For example, crude oil extracted from Alaskan reserves is piped many miles en route to refineries. As with friction related to the transport through conduits of any fluid, friction encountered in pumping of hydrocarbon fluids through conduits such as pipelines results in pressure drop along the length of the conduit. Moreover, at the high volumetric flow rates desired for transport of the hydrocarbon fuels, laminar flow tends to give way to highly turbulent flow, resulting in even greater friction related pressure loss. Thus, large amounts of additional energy must be expended to overcome the drag inherent in the flow of the fuel through the pipeline.
Accordingly, certain techniques have been employed in attempts to reduce the frictional drag encountered in transportation of hydrocarbon fuels. For example, as illustrated by U.S. Pat. No. 4,625,745, U.S. Pat. No. 3,748,266, U.S. Pat. No. 3,758,406 and U.S. Pat. No. 3,654,994, various agents for reducing friction have been added to hydrocarbon fluids. Typically, these agents alter the characteristics of the fluid so that at the fluid velocity which otherwise produced highly turbulent flow, produces less turbulent or laminar flow. Thus, pressure loss due to friction during transport of the fluid through conduits is reduced.
Nevertheless, conventional friction reduction agents have been found to suffer several drawbacks. For example, although effectiveness of the agents generally increases with increased molecular weight of the agents, the hydrocarbon or oil solubility of the agent characteristically decreases with higher molecular weight. Thus, either relatively less effective agents or lower concentrations of relatively more effective agents can be used, and so the efficacy of conventional agents is limited. Moreover, agents such as described in U.S. Pat. No. 3,654,994 often require special handling and equipment, are relatively expensive and are available generally only in relatively dilute forms, i.e., about 5% active mixtures.